In the planning of injection molds, in some commodity plans have been specified, but in many of the mold planning by the mold planners to set. Generally speaking, in the plane on the face of the face of a simple disposal, and sometimes encountered three-dimensional way of the sub-surface should pay special attention. The selection of the sub-surface should follow the following guidelines: 1. Plastic mold manufacturer pointed out that does not affect the appearance of finished products, especially the appearance of a clear requirement of finished products, should pay attention to the appearance of the face of the impact; 2. is conducive to ensuring the accuracy of finished products; 3. conducive to mold processing, especially cavity processing; 4. is conducive to pouring system, exhaust system, cooling system planning; 5. is conducive to the demolding of finished products to ensure that the finished product in the mold to stay on the side; 6. Easy to install the device. Injection mold on the diversion channel has the following six requirements 1. Plastic mold manufacturer pointed out that the plastic flow through the bypass when the pressure loss and temperature loss is small. 2. Shunt channel curing time should be later in the finished product curing time, in order to facilitate the pressure transmission and packing. 3. Ensure that the plastic into the cavity evenly and evenly. 4. Plastic mold manufacturer pointed out that the length of the diversion channel should be as short as possible, its volume to be small. 5. To facilitate processing and tool selection. 6. Each section of the channel than the next section of the flow channel 10-20% or so.